Thallus: foliose, adnate to loosely adnate, 3-15 cm in diam., lobate; lobes: subirregular, elongate, slightly imbricate, plane, separate, 5-20 mm wide; apices: rotund, becoming crenate and dissected with age, sometimes ascending, ciliate; cilia: up to 3.0 mm long; upper surface: gray with some blackened areas, smooth, dull to shiny, epruinose, emaculate, finely reticulately cracked with age; isidia: simple to coralloid branched, sometimes disintegrating with age, often apically ciliate, common, laminal and marginal; soredia and pustulae: absent; medulla: white with continuous algal layer; lower surface: black with brown naked zone peripherally, centrally rhizinate, rhizines simple, black; Apothecia: rare, substipitate, up to 8 mm in diam.; margin: sparsely isidiate; disc: brown, imperforate; ascospores: ellipsoid, 21-35 x 11-18 µm; Pycnidia: not seen; Spot tests: upper cortex K+ yellow, C-, KC-, P-; medulla K+ yellow turning orange, C-, KC-, P+ orange; Secondary metabolites: upper cortex with atranorin and chloroatranorin; medulla with stictic acid (major) and constictic acid (minor), menegazziaic acid (trace).; Substrate and ecology: usually on hardwood trees in open habitats, rarely on rocks or soil; World distribution: pantropical and pantemperate; Sonoran distribution: SE Arizona southwards along the Sierra Madre Occidental in Chihuahua, Baja California and in the mountains of southern Baja California Sur.